Pneumatic hammer.



' 6. H. JHNSUN.

i PNEUMATIC HAMMER.

(Application lfad June 10, 1901.3

(No Model.)

l UNrrs STATES CHARLES HARRIS JoHNSoN, or oHIoAcoI-VIEIGI-ITS, -ILLINOIS PN EU MATIQ HAMMER.

SPECIFICATION forming part of :LettersA Patent N o. 695,396, dated March 11, 11902. l

Application filed June 10, 1901. Serial No. 63,957. (No model.)

vTo aZZ whom it may concern:

Beitknown thatI, CHARLES HARRIS JOHN- SON, a citizen of the United States, residing at Chicago Heights, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Pneumatic Hammers; and I hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing, in which is shown a longitudinal central section of a construction embodying my invention.

My invention relates generally to that class of motive iuid operated tools commonly` termed pneumatic hammers or riveters, and especially to the class of hand tools wherein are combined a cylinder anda differential piston, with suitable ports and means for maintaining a constant motive-fluid pressure on that head of the piston having the lesser area.

The mainobjects of myinvention are, first,

to simplify the construction of thisclass of pneumatic tools, and, second, yto uniformly increase the piston mass toward its hammer end or that head having the greater area,'so as to add to the efficiency of the blow, while reducing the piston mass to be suddenly arrested by the metal at the front end of the piston.

To this end the invention may be generally Stated as residing in the combination of a suitable cylinder and a differential piston, the

cylinder having an exhaust-port in that end thereof corresponding to the piston-head having the greater area and the piston havinga through-passage or supply-port for that end of the cylinder which contains the exhaustport, said supply-passage of the piston being constantly open to the pressure-supply, and means for maintaining a constant motivel `iiuid pressure upon that head of the piston having the lesser area.

I-will now proceed to describe my invention more .fully by reference to the drawing, so that others skilled inthe art to which it appertains may apply `the same.

Inthe drawing, A indicates a suitable cylinder, some of the internal diameters of which will correspond with the piston to be used therewith, while others may exceed the same for purposes which will hereinafter appear.

The lower end of said cylinderA will be prol Y vided with a ferrule A for the reception of a snap or die a, commonly Vused with this class of tools, and'said ferrule and snap will when in place constitute one head of'the cyl-` inder, the opposite head of the cylinder being constituted by the screw `plug or cap C ,which latter also serves to unite the handle D with the cylinder A. The ferrule A may be proof the cylinder containing the lesser head of' the differential piston, and said supply-passage d is provided with the usual or any approved throttle-valve E, which may be operated by a suitable lever e, pivoted on the han-` dleD. v

The central portion of the cylinder A is of 6o i vided with a flange or collar d' and introduced p f an internal diameter corresponding to thediameter ofthat head of the piston having the greater area, as at; l 1, and is increased at one end, (or at the lower end ofthe cylinder,) as at 2 2, to aiford a clearance fork the piston and at the other end, (or above,) as at 3 3, to re`- ceive an inserted sleeve 4, which reduces the inner Ldiameter of the cylinder to correspond with that head of the piston havingV the lesser area. t

The inserted sleeve 4 for reducingthe internal diameter of the cylinder permits the ferrule A? and the piston 7 to be inserted from the upper or handle end of the cylinder, thus simplifying the construction and reducing the number of joints of the device.

5 indicates an exhaust-port, and 6 a reliefport forv preventing any pressure from leakage on the reverse stroke of the piston.

` 7 indicates a differential' piston oftubular form or having a hollow center 7 a, (see dotted lines,) which is open toward the motive-fluid supply d of the cylinder and closed at the opradially-arranged ports or passages 7", (see y ICO posite or hammer end except for one or more sure until the ends of the supply-ports 7b are closed by the walls of the cylinder and then by expansion until the lower end of the piston passes and opens the exhaust-port c of cylinder A, when exhaust occurs, the motion of the piston is reversed, and its hammer blow is delivered. Just before the hammer blow is struck the supply-ports 7'b are opened, and the lift or return movement of the piston will commence as soon as its blow has been delivered.

The arrangement of the su pply-ports which pass through the piston and the exhaust port or ports of the cylinder is such that the piston-ports 7b never act as exhaust-ports, and the relative arrangement of said ports will determine the length and rapidity of the piston movement.

It will be noted that a characteristic feature of the present construction is the admissionport which passes through the piston and the formation at the lower end of the piston which cuts 0E the supply of air to the under side, and the particular value of such a construction resides in the fact that it is not necessary to close the back end of the piston, and in consequence the weight of the piston can be uniformly increased from the back end downward, (or to the hammer end,) thus causing the least possible mass to be suddenly stopped by the metal at the front of the piston.

I-Iaving thus described my invention, what I claim, and desire to secure by Letters Patent, is

l. In a constant-pressure motive-finid-operated hammer, the combination with a cylin` der having an exhaust-port, of a differential piston having a through supply port or passage which is constantly open to the motivefluid-pressure supply, and means for closing the delivery end of the through-passage before the exhaust-port of the cylinder is opened, substantially as and for the purposes specified.

2. In a constant-pressure motive-fluid-operated hammer, the combination with a cylinder having an exhaust-port, of a hollow differential piston open at the head having the lesser area and provided with a radial supply port or passage at its opposite end, substantially as and for the purposes specified.

3. In a motive-fluid-operated hammer, th-e combination of a cylinder and a differential piston, the piston having a supply-port therethrough and which opens on the lesser head of the piston, and the cylinder having an exhaust-port at that end of the cylinder' which contains the head of the piston having the greater area, and means for maintaining a constant motive-fluid pressure in that end of the cylinder which contains the piston-head having the lesser area, substantially as and for the purposes specified.

In testimony whereof I affix my signature, in presence of two witnesses, this 3d day of June, 1901.

CHARLES HARRIS JOHNSON.

lVitnesses:

H. H. VAUGHAN, G. I. McELDoWNEY. 

